/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// Copyright (c) 1996-2018 Live Networks, Inc.  All rights reserved.
// Generic Hash Table
// C++ header

#ifndef _HASH_TABLE_HH
#define _HASH_TABLE_HH

#ifndef _BOOLEAN_HH

#include "Boolean.hh"

#endif

class HashTable {
public:
    virtual ~HashTable();

    // The following must be implemented by a particular
    // implementation (subclass):
    static HashTable *create(int keyType);

    virtual void *Add(char const *key, void *value) = 0;

    // Returns the old value if different, otherwise 0
    virtual Boolean Remove(char const *key) = 0;

    virtual void *Lookup(char const *key) const = 0;

    // Returns 0 if not found
    virtual unsigned numEntries() const = 0;

    Boolean IsEmpty() const { return numEntries() == 0; }

    // Used to iterate through the members of the table:
    class Iterator {
    public:
        // The following must be implemented by a particular
        // implementation (subclass):
        static Iterator *create(HashTable const &hashTable);

        virtual ~Iterator();

        virtual void *next(char const *&key) = 0; // returns 0 if none

    protected:
        Iterator(); // abstract base class
    };

    // A shortcut that can be used to successively remove each of
    // the entries in the table (e.g., so that their values can be
    // deleted, if they happen to be pointers to allocated memory).
    void *RemoveNext();

    // Returns the first entry in the table.
    // (This is useful for deleting each entry in the table, if the entry's destructor also removes itself from the table.)
    void *getFirst();

protected:
    HashTable(); // abstract base class
};

// Warning: The following are deliberately the same as in
// Tcl's hash table implementation
int const STRING_HASH_KEYS = 0;
int const ONE_WORD_HASH_KEYS = 1;

#endif
